Air Cooled Faraday Shield and Methods for Using the Same

ABSTRACT

A chamber is provided. The chamber includes a Faraday shield positioned above a substrate support of the chamber. A dielectric window is disposed over the Faraday shield, and the dielectric window has a center opening. A hub having an internal plenum for passing a flow of fluid received from an input conduit and removing the flow of fluid from an output conduit is further provided. The hub has sidewalls and a center cavity inside of the sidewalls for an optical probe, and the internal plenum is disposed in the sidewalls. The hub has an interface surface that is in physical contact with a back side of the Faraday shield. The physical contact provides for a thermal couple to the Faraday shield at a center region around said center opening, and an outer surface of the sidewalls of the hub are disposed within the center opening of the dielectric window.

CLAIM OF PRIORITY

This application is a Divisional of U.S. patent application Ser. No.15/885,728, filed on Jan. 31, 2018 (U.S. Pat. No. 10,690,373, issued onJun. 23, 2020), entitled “Air Cooled Faraday Shield and Methods forUsing the Same”, which is a Continuation of U.S. patent application Ser.No. 13/974,324, filed on Aug. 23, 2013 (U.S. Pat. No. 9,885,493, issuedon Feb. 6, 2018), entitled “Air Cooled Faraday Shield and Methods forUsing the Same”, which further claims the benefit of and priority to,under 35 U.S.C. 119§(e), to U.S. Provisional Patent Application No.61/847,407, filed on Jul. 17, 2013, and titled “Air Cooled FaradayShield and Methods for Using the Same”, which are hereby incorporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to semiconductor fabrication,and more particularly, to a chamber containing a Faraday shield used inplasma etching apparatus.

DESCRIPTION OF THE RELATED ART

In semiconductor manufacturing, etching processes are commonly andrepeatedly carried out. As is well known to those skilled in the art,there are two types of etching processes: wet etching and dry etching.One type of dry etching is plasma etching performed using an inductivelycoupled plasma etching apparatus, such as transformer coupled plasma(TCP) chambers.

A plasma contains various types of radicals, as well as positive andnegative ions. The chemical reactions of the various radicals, positiveions, and negative ions are used to etch features, surfaces andmaterials of a wafer. During the etching process, a chamber coilperforms a function analogous to that of a primary coil in atransformer, while the plasma performs a function analogous to that of asecondary coil in the transformer.

The reaction products generated by the etching process may be volatileor non-volatile. The volatile reaction products are discarded along withused reactant gas through the gas exhaust port. The non-volatilereaction products, however, typically remain in the etching chamber. Thenon-volatile reaction products may adhere to the chamber walls and adielectric window. Adherence of non-volatile reaction products to thewindow may interfere with the etching process. Excessive deposition mayresult in particles flaking off the window onto the wafer, thusinterfering with the etching process. In some embodiments, a Faradayshield is utilized inside the chamber, such that the Faraday shieldblocks deposition onto the window. In such cases, the deposition willthen build up on the Faraday shield, which can also lead to particlesflaking off or peeling off over time. Coatings of the Faraday shielditself can also peel off if excessive temperatures are applied to theFaraday shield for extended periods of time.

In TCP chambers, power, which heats the chamber and associated parts, isprimarily delivered via TCP coils, which resided over the window. Duringetch processes, a chamber and its parts may cycle through various steps,causing heat from the processes to similarly cycle level e.g., from hotto very hot, or cold to hot, hot to cold, etc. When the Faraday shieldreceives such deposition, the temperature cycling itself may lead tosuch flaking or pealing of the deposition material. Currently, toaddress this issue, chambers are required to be cleaned frequently orwhen it is determined that deposition (e.g., etch byproducts) residingin the Faraday shield may flake off or peel, and ultimately land onwafers being processed.

It is in this context that embodiments of the inventions arise.

SUMMARY

Plasma processing chambers utilize radio frequency (RF) power togenerate the plasma in the chamber. The RF power is typically introducedvia a dielectric (ceramic or quartz window) and can also be coupledthrough coated (e.g., anodized) Faraday shields (e.g., grounded metal orfloating dielectric), which are immersed in the plasma environment. RFinduced heating increases the temperatures of the Faraday shield duringplasma processing and can severely increase the Faraday shieldtemperature beyond a threshold above which anodized coating or depositedplasma byproducts start to flake and/or peel off, which may produceparticles and defect issues on wafer. The embodiments defined hereinprovide methods and structures for controlling and/or maintaining thetemperature of the Faraday shield for successful operation and minimizethermal cycling issues.

In one embodiment, a chamber is provided. The chamber includes a Faradayshield positioned above a substrate support of the chamber. A dielectricwindow is disposed over the Faraday shield, and the dielectric windowhas a center opening. A hub having an internal plenum for passing a flowof fluid received from an input conduit and removing the flow of fluidfrom an output conduit is further provided. The hub has sidewalls and acenter cavity inside of the sidewalls for an optical probe, and theinternal plenum is disposed in the sidewalls. The hub has an interfacesurface that is in physical contact with a back side of the Faradayshield. The physical contact provides for a thermal couple to theFaraday shield at a center region around said center opening, and anouter surface of the sidewalls of the hub are disposed within the centeropening of the dielectric window.

In one embodiment, an apparatus for use in a plasma chamber is provided.The apparatus includes a Faraday shield for coupling to a top region ofa plasma chamber. The Faraday shield has a process side that face insideof the plasma chamber and a center opening. The apparatus includes a hubhaving an internal plenum for passing a flow of fluid received from aninput conduit and removing the flow of fluid from an output conduit. Thehub has sidewalls and a center cavity inside of the sidewalls for anoptical probe. The internal plenum is disposed in the sidewalls and thehub includes an interface surface that is in physical contact with aback side of the Faraday shield. The physical contact provides for athermal couple to said Faraday shield at the center region around saidcenter opening. The center region in the back side of the Faraday shieldincludes a plenum that mates with the internal plenum of the hub. Theinterface surface of the hub surrounds the plenum of the Faraday shieldand a thermal couple to the back side of the Faraday shield is definedat the interface surface.

In one embodiment, flowing air via elevated rates or preset rates to ahub that interfaces with a Faraday shield can assist in reducing thetemperature of the Faraday shield near the center region. This providesa method and system of controlling the temperature of the Faraday shieldand reducing the wide cycle swings in temperature during operation.

In one embodiment, compressed dry air (CDA) provides a way of coolingthe Faraday shield with the aid of an air-path directing plenum thatchannels the air into a central hub that removes the excess heat andmoves it out into the TCP coil enclosure. In one embodiment, compresseddry air (CDA) equivalent to 10 cubic feet per minute (CFM) flows orhigher and at high inlet pressures in the range of 10-20 pounds persquare inch (PSI) enable super convective flows in narrow air plenums.Other example parameters are described below.

In one example, the plenums are attached to a central air-delivery hubthat supports one or multiple streams of air inlet and outlets foroptimal mixing and heat removal from the Faraday shield's internalcontact face and reduces the operating temperature of the shield andminimizes thermal cycling issues.

In another embodiment, instead of CDA, it is possible to use air withair-amplifiers for enhanced flow or liquid based cooling. In addition,air amplifiers may also be adapted to a variety of air-channeling plenumdesigns that optimize the air pathway and generate uniform temperaturedistribution and provide a wide range of window cooling options forinternal Faraday shields and/or components in RF or plasma environments.

In one embodiment, a Faraday shield system for use in a plasmaprocessing chambers is provided. The system includes a disk structuredefining a Faraday shield, and the disk structure has a process side anda back side. The disk structure extends between a center region to aperiphery region. The disk structure resides within the processingvolume. The system also includes a hub having an internal plenum forpassing a flow of air received from an input conduit and removing theflow of air from an output conduit. The hub has an interface surfacethat is coupled to the back side of the disk structure at the centerregion. A fluid delivery control is coupled to the input conduit of thehub. The fluid delivery control is configured with a flow rateregulator. The regulated air can be amplified or compressed dry air(CDA). The system includes a fluid removal control coupled to the outputconduit for removing the flow of air from the plenum of the hub. Theplenum of the hub defines a loop into and out of the hub, and that theflow of air is isolated from the processing volume. A controller isprovided for managing the flow rate regulator that sets the flow rate ofthe flow of air.

In another embodiment, a plasma processing apparatus is disclosed. Theapparatus includes a chamber having walls and a substrate supportdefined in a processing volume, and a Faraday shield. The Faraday shieldhas a disk shape with a process side and a back side, and the disk shapeextends between a center region to a periphery region. The Faradayshield is defined within the processing volume, such that the processside faces the substrate support. The apparatus includes a hub having aninternal plenum for passing a flow of fluid received from an inputconduit and removing the flow of fluid from an output conduit. The hubhas an interface surface that is thermally coupled to the back side ofthe Faraday shield at the center region. A fluid delivery control iscoupled to the input conduit of the hub, the fluid delivery control isconfigured with a flow rate regulator for setting a flow rate of theflow of fluid through the plenum of the hub. A fluid removal control iscoupled to the output conduit for removing the flow of fluid from theplenum of the hub.

In still another embodiment, a method for controlling a temperature of aFaraday shield disposed inside a process volume of a plasma processingchamber is disclosed. The method includes thermally coupling a hub to aback side of the Faraday shield at a center region of the Faradayshield. The hub has a plenum for receiving air and removing air, suchthat air communicates through the plenum. The method includes supplyinga flow of air into a plenum to the hub. The flow of air into and out ofthe plenum is maintained outside of the process volume. The method alsoincludes regulating a flow rate of the air into the plenum. Theregulating is configured to manage adjustments temperature of the hub atthe thermal couple to the center region of the Faraday shield. Theregulating is correlated to processing steps performed in the processvolume. In one embodiment, increases in flow rate of the air reduce atemperature of the center region of the of the Faraday shield causingheat conductance through the Faraday shield toward the center region.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with further advantages thereof, may best beunderstood by reference to the following description taken inconjunction with the accompanying drawings.

FIG. 1 illustrates a plasma processing system utilized for etchingoperations, in accordance with one embodiment of the present invention.

FIG. 2A illustrates a portion of a chamber used in plasma processing,having a Faraday shield interfaced with a hub for conducting heat awayfrom the Faraday shield from outside of a processing volume, inaccordance with one embodiment of the present invention.

FIG. 2B illustrates another simplified example of a chamber having a huband the interface surfaces of the hub for contacting the Faraday shieldand optionally the dielectric window, in accordance with one embodimentof the present invention.

FIGS. 2C-2E illustrate exemplary alternative interfaces or constructionsof the hub and/or the hub and Faraday shield, in accordance with oneembodiment of the present invention.

FIG. 2F illustrates a graphical representation of heat conductancethrough a body of the Faraday shield toward the center region of theFaraday shield, in accordance with one embodiment of the presentinvention.

FIGS. 3A-3D illustrate other alternate hub constructions, interfaces,plenums and modifications to the center region of the Faraday shield, inaccordance with one embodiment of the present invention.

FIGS. 4A-4B illustrate still another alternate hub construction, andinterface surfaces to the dielectric window in addition to interfaceswith the Faraday shield, in accordance with one embodiment of thepresent invention.

FIGS. 5A-1 and 5A-2 illustrate example temperature variations of thedielectric window (when in contact with the hub or placed proximate tothe hub), and the associated changes based on changes in flow rates ofair, in accordance with one embodiment of the present invention.

FIGS. 5B-1 and 5B-2 illustrate example temperature variations of theFaraday shield and associated based on changes in flow rates of air, inaccordance with one embodiment of the present invention.

FIGS. 6A and 6B illustrate example method operations for using a Faradayshield with a hub for air cooling of the center region of the Faradayshield to cause heat conductance out of the Faraday shield from outsideof the processing volume, in accordance with one embodiment of thepresent invention.

DETAILED DESCRIPTION

Disclosed are apparatus used in etching semiconductor substrates andlayers formed thereon during the manufacture of semiconductor devices.The apparatus is defined by a chamber in which etching is performed. AFaraday shield is disposed within the chamber. A hub is configured tointerface with the Faraday shield, such that the contact provides athermal interface. The hub is connected to a plurality of conduits thatdeliver fluid and remove fluid from the hub, such that the fluid isdelivered at a rate of increased flow through the hub. The plurality ofconduits connect to a plenum inside of the hub, such that the fluidenters the hub and leaves the hub.

In one embodiment, the hub is a separate structure that couples andinterfaces thermally with the Faraday shield (and optionally also withthe window) or is a structure that is integrated with the Faradayshield.

The fluid, in one embodiment, is air. The air, in one embodiment, iscompressed dry air (CDA). By flowing air to and from the hub, which isthermally connected to the Faraday shield, a temperature of the Faradayshield at the location of the interface is caused to decrease, relativeto an increased temperature of the Faraday shield during operation ofthe chamber. In one embodiment, the air is flown through a plenum of thehub at a set flow rate that is pre-computed, selected or regulated toreduce a temperature of the Faraday shield and/or the dielectric window.

For example, during operation of the chamber, a TCP coil provides powerto the chamber, so as to define a plasma within the chamber. The TCPcoil is disposed above a dielectric window and the Faraday shield isdisposed below and adjacent to the dielectric window. In thisconfiguration, the TCP coil will heat up the window and the Faradayshield. During processing cycles, the heat will fluctuate up and down,causing the aforementioned heat differentials.

Therefore, by flowing air to and from the hub (i.e., through), which isin thermal contact with at least a center region of the Faraday shield,the temperature of the Faraday shield at and around the vicinity of thecenter region is caused to be reduced. The reduced temperature in andaround the center region of the Faraday shield will cause a temperaturedifferential along the Faraday shield, such that heat will conduct alongthe Faraday shield (i.e., in the bulk body of the Faraday shield) fromhot to cold (e.g., toward the hub). In one embodiment, conducting fromhot to cold means that the hotter surfaces of the Faraday shield whichare away from the center region (e.g., the periphery and between theperiphery and center of the Faraday shield) will decrease in temperatureas heat conducts toward the cooler center region of the Faraday shield.

It will be apparent to one skilled in the art that the present inventionmay be practiced without some of these specific details. In otherinstances, well known process operations and implementation details havenot been described in detail in order to avoid unnecessarily obscuringthe invention.

FIG. 1 illustrates a plasma processing system utilized for etchingoperations, in accordance with one embodiment of the present invention.The system includes a chamber 102 that includes a chuck 103, adielectric window 104, and a Faraday shield 108. The chuck 103 can be anelectrostatic chuck for supporting the substrate when present. Alsoshown is an edge ring 116 that surrounds chuck 103, and has an uppersurface that is approximately planar with a top surface of a wafer, whenpresent over chuck 103. Chamber 102 also includes a lower liner 110 thatis coupled to an upper liner 118, also referred to as a pinnacle. Theupper liner 118 is configured to support the Faraday shield 108. In oneembodiment, the upper liner 118 is coupled to ground and thereforeprovides ground to the Faraday shield 108. A space is provided betweenthe Faraday shield 108 and the dielectric window 106. Excess gases 114are removed from the process volume of the chamber via exhaust plate112.

Further shown is an RF generator 160, which can be defined from one ormore generators. If multiple generators are provided, differentfrequencies can be used to achieve various tuning characteristics. Abias match 162 is coupled between the RF generators 160 and a conductiveplate of the assembly that defines the chuck 103. The chuck 103 alsoincludes electrostatic electrodes to enable the chucking and dechuckingof the wafer. Broadly, a filter 164 and a DC clamp power supply isprovided. Other control systems for lifting the wafer off of the chuck103 can also be provided. Although not shown, pumps are connected to thechamber 102 to enable vacuum control and removal of gaseous byproductsfrom the chamber during operational plasma processing.

The Faraday shield has a central region that will allow a showerhead todeliver process gases into the processing volume of the chamber 102.Additionally, other probing apparatus can also be disposed through theFaraday shield 108 near the central region, where the hole is provided.The probing apparatus can be provided to probe process parametersassociated with the plasma processing system, during operation. Probingprocesses can include endpoint detection, plasma density measurements,ion density measurements, and other metric probing operations. Thecircular shape of the Faraday shield 108 is defined due to the geometryof a typical wafer, which is usually circular. As is well known, waferstypically are provided in various sizes, such as 200 mm, 300 mm, 450 mm,etc.

Disposed above the Faraday shield 108 is the dielectric window 104. Asnoted above, the dielectric window 104 can be defined from a quartz typematerial. Other dielectric materials are also possible, so long as theyare capable of withstanding the conditions of a semiconductor etchingchamber. Typically, chambers operate at elevated temperatures rangingbetween about 50 Celsius and about 160 Celsius. The temperature willdepend on the etching process operation and specific recipe. The chamber102 will also operate at vacuum conditions in the range of between about1 m Torr (mT) and about 100 m Torr (mT). Although not shown, chamber 102is typically coupled to facilities when installed in a clean room, or afabrication facility. Facilities include plumbing that provideprocessing gases, vacuum, temperature control, and environmentalparticle control.

These facilities are coupled to chamber 102, when installed in thetarget fabrication facility. Additionally, chamber 102 may be coupled toa transfer chamber that will enable robotics to transfer semiconductorwafers into and out of chamber 102 using typical automation.

Continuing with reference to FIG. 1, the TCP coil is shown to include aninner coil (IC) 122, and an outer coil (OC) 120. The TCP coil is placedand arranged over the dielectric window 104, which is respectivelyplaced over the Faraday shield 108. In one embodiment, match components128 and RF generators 126 are provided, as coupled to the coils. In oneembodiment, the chamber will be connected to a controller that isconnected to the electronics panel of chamber 102. The electronics panelcan be coupled to networking systems that will operate specificprocessing routines that depend on the processing operations desiredduring specific cycles. The electronics panel can therefore control theetching operations performed in chamber 102, as well as control thedelivery and removal of fluid to a hub, when air cooling the Faradayshield 108.

FIG. 2A shows a system diagram 200, of a hub 202 that is used to aircool Faraday shield 108, in accordance with one embodiment of thepresent invention. In this example, the hub 202 is a structure thatcouples to the Faraday shield 108 and fits into an opening of thedielectric window 104. This configuration allows hub 102 to provide aircooling transfer to both the Faraday shield 108 and the dielectricwindow 104. For instance, the hub 102 has exterior surfaces that areplaced in contact with surfaces of the Faraday shield 108 and the window104.

As shown, an interface 204 is provided between the hub and windowinterface. An interface 206 is provided between the hub and Faradayshield 108. Broadly speaking, the surfaces of the hub 102 are placed incontact with the surfaces of the Faraday shield 108, and optionally alsowith the dielectric window 104. The contact, in one embodiment isthermal contact. For instance, if the surfaces are placed adjacent toeach other, closer placement will provide better thermalinterconnection, while direct physical contact will provide betterthermal interconnection. In one embodiment, the thermal interconnectionis designed such that the interface 206 with the hub 202 is in directphysical contact with the Faraday shield 108.

In one embodiment, the hub 202 will include a plurality of inputconduits 202 a and output conduits 202 b, which are connected toconnection lines 207 and 208, respectively. The connection line 207couples to fluid delivery control 210. Fluid delivery control 210receives fluid from a compressed dry air (CDA) source 212, or an airsupply 214 a that is coupled to an air amplifier 214 b. In oneembodiment, the controller can define which input the fluid deliverycontrol 210 will select. In another embodiment, fluid delivery control210 is connected via plumbing or facilities lines or tubes, that use CDA212 or the air supply/air amplifier 214.

In one configuration, fluid delivery control 210 uses fluid flows thatare selected to have a particular flow rate. In one embodiment, theplenum of the hub defines a loop into and out of the hub, such that theflow of fluid is maintained outside of the processing volume. That is,no fluid passed through the hub will enter the sealed processing volumethat is under pressure and filled with processing gas during operation.Further, the flow of fluid provides for a reduced temperature at thecenter region of the Faraday shield, and the reduced temperature in thecenter region induces a conductive flow of heat through the Faradayshield toward the center region.

Flow rates that are believed useful for cooling the Faraday shield 108can range between 0.5 CFM (cubic feet per minute) to 20 CFM. Inexperimental testing, flow rates tested include 1 CFM, 5 CFM, and 10CFM, although higher flow rates are believed to be possible. As will bediscussed below, sufficient cooling was observed when flow rates of 5CFM and 10 CFM were used. If CDA 212 is used, the compressed nature ofCDA 212 will cause the flow to reach flow rates of 1-10 CFM. If an airsupply 214 a is used, an air amplifier 214 b is needed to produce flowrates between 0.5 CFM and 20 CFM. It is believed that even higher flowrates than 20 CFM may be useful, for instance up to 60 or 50 CFM.

In one embodiment, depending on the configuration of the Plenum usedwithin the hub 202, the pressure at the input of the hub can vary. In ahub used for experimental testing, the pressures at the input of the hubwere measured to be between 10 and 25 pounds per square inch (PSI). Muchhigher pressures can be used at the source, as the pressure may dropjust before delivery to the hub input(s). For the experimental testingwhere 1 CFM was set, the PSI at the input was measured at 14.7 PSI,where 5 CFM was set, the PSI at the input was measured at 15.5 PSI,where 10 CFM was set, the PSI at the input was measured at 17 PSI.

It is believed that the flow of air into the Plenum of the hub 202 andout of the Plenum 22 provides for a circulation and/or communication ofair that reduces or removes heat from within the hub 202. The hub 202,without the circulating air flow could increase in temperature matchingor approximately matching the temperature of the Faraday shield 108, ifplaced in thermal contact with the Faraday shield 108. However, becausethe air flow into and out of the Plenum of the hub 202 reduces the heatwithin the Plenum, such as at the region of the interface between thehub and the Faraday shield 108, heat is removed.

Connection line 208 is coupled to a fluid removal control 213 that isconnected to the output conduits 202 b of the hub 202. Fluid removalcontrol 213 can be coupled to vacuum 216 or a passive exhaust 217. Inone embodiment, if vacuum 216 is used, fluid removal control 213 canpull on the fluid passing through the Plenum of the hub 202, whichassists in expediting the flow of air provided by fluid delivery control210. In the case of passive exhaust 217, the fluid removal control 213simply removes the fluid (i.e. air) from the hub 202 and dispenses itappropriately within the facilities of the chamber clean room.

In one embodiment, the fluid delivery control 210 includes a flow rateregulator, and optionally includes a pressure regulator. In anotherembodiment, a flow regulator and/or the pressure regulator is/areseparate components from the fluid delivery control 210. In oneembodiment, a controller 240 can control one or more valves orcommunicates control data to the fluid delivery control to set orregulate the flow rate provided to the hub 202.

Although air is described to be the fluid used with hub 202, otherfluids may also be used. For instance, liquids can also be used andchanneled through hub 202. In still other embodiments, the fluids can begases, such as nitrogen, helium, etc.

In other embodiments, the liquids or air can be cooled in advance, suchthat the fluid delivery control 210 provides the fluid at a reducedtemperature.

In one embodiment, a system for use in a plasma processing chambers isprovided. The system includes a disk structure defining the Faradayshield, and the disk structure has a process side and a back side. Thedisk structure extends between a center region to a periphery region(e.g., an area near or at the edge of the Faraday shield). The diskstructure resides within the processing volume. The system also includesa hub 202 having an internal plenum for passing a flow of air receivedfrom an input conduit and removing the flow of air from an outputconduit. The hub has an interface surface that is coupled to the backside of the disk structure (e.g., having a disk shape) at the centerregion.

A fluid delivery control 210 is coupled to the input conduit of the hub202. The fluid delivery control is configured with a flow rateregulator. The regulated air can be amplified 214 or compressed dry air(CDA) 212. The system includes a fluid removal control 213 coupled tothe output conduit for removing the flow of air from the plenum of thehub 202. The plenum of the hub defines a loop into and out of the hub,and that the flow of air is isolated from the processing volume. Theloop can take on many configurations and paths. The loop can be simplein and out or can travers in nonlinear paths inside of the hub or inplenums formed in the Faraday shield (e.g., as shown in FIG. 3B below).A controller 240 is provided for managing the flow rate regulator thatsets the flow rate of the flow of air.

FIG. 2B illustrates an embodiment where the hub 202 is coupled to theFaraday shield 108 and the window 104, in accordance with one embodimentof the present invention. In this example, the coupling is thermalcoupling. Thermal coupling means that the surface of the hub 202 is inphysical contact with a surface of the Faraday shield 108 and or thewindow 104. For instance, the hub can be in physical contact atinterface 204 and interface 206, with the window 104 and Faraday shield108, respectively. Thermal coupling simply means that the surfaces ofthe hub or air flow is in direct physical contact with the Faradayshield or window, or the hub is in close proximity (e.g., withoutphysical contact or minimal contact) that its temperature can impact thetemperature of an adjacent structure.

In one embodiment, the hub 202 is defined from a temperature conductivematerial. The temperature conductive material can be a metal. The metalcan be aluminum, stainless steel, copper or combinations of metals andalloys that thermally conduct heat. In one embodiment, the surfaceinterfaces of the hub 202 are configured or fabricated to provide evensurface contact with the thermally conductive surfaces of the Faradayshield 108 and the window 104. Fabricating the surfaces can include,polishing the surfaces so that the surfaces mate and provide a thermalconnection when placed in physical contact with one another. In otherembodiments, glues or adhesives that thermally conduct can also beplaced between the hub and the surfaces of the Faraday shield 108 and orthe window 104.

In the illustration of FIG. 2B, the hub 202 includes a Plenum within thehub, such that fluids flow into the hub and flow out of the hub. Asmentioned above, fluid delivery control 210 can deliver the fluids tothe hub 202 and fluid removal control 213 can remove the fluids from thehub 202. Fluid delivery control 210 is coupled to supplies, such asfacility supplies that can provide the correct fluid selected for theconfiguration or process. A controller 240 is shown communicating with afluid delivery control 210 and the fluid removal control 213. Controller240 is in communication with system electronics that may include aninterface for controlling and setting recipes for use when processingwafers in chamber 102.

As mentioned above, the chamber 102 is used to process etchingoperations using plasma, which can etch features or surfaces ormaterials of the wafer, which is placed on a Chuck support 103. RFsupplies are communicated and coupled to the Chuck support 103, and RFTCP coils 120/122 are disposed over the window 104 to provide power tothe plasma of the chamber 102, during operation. Also shown is a gasinjector 230 and an optical probe 232. The gas injector 230 and opticalprobe 232 are, in one embodiment disposed between a center region of thehub 202. The gas injector 230 is provided for injecting gas into thechamber during operation, and the optical probe 232 is provided tomeasure and provide endpoint detection of the processes occurring withinthe chamber during plasma processing.

In one embodiment, the gas injector is defined in a center cavity of thehub, and the gas injector is defined for providing process gas into theprocessing volume. In one embodiment, the optical probe is defined in acenter cavity of the hub, and the optical probe is defined formonitoring process conditions in the processing volume during use. Thecenter cavity may be tubular, square or other shapes. The center cavityextends through the Faraday shield 108 and the window. A seal is madebetween the gas injector in the hub, such that the process volume isclosed to conditions outside of the chamber. The hub and its airsupplies are external to the chamber, such that it hub is isolated fromthe processing volume.

FIG. 2C illustrates an example where the hub 202 is separate from theFaraday shield 108. In this embodiment, the hub 202 is configured to beplaced in physical contact with the Faraday shield 108. The physicalcontact will be such that the bottom interface surfaces 250 of the hub202 will contact an interface surface 262 of the Faraday shield 108. Inother embodiments, the side interface surfaces 252 of the hub 202 canalso be placed adjacent to other surfaces, such as the window 104, asshown in FIG. 2B. As such, the hub 202 can be assembled and connected tothe Faraday shield 108 using any connection means, such as screws,clamps, surface indentations, clips, glue, adhesives, or combinationsthereof.

FIG. 2D illustrates an example where an alternative hub 202′ isprovided, in accordance with another embodiment of the presentinvention. In this embodiment, the hub 202′ is integrated with theFaraday shield 108. The integrated construction allows for the hub to beat least partially disposed within the surface or body of the Faradayshield 108. That is, the hub portion is allowed to be unified with theshield portion, such that the Plenum is allowed to communicate air forcooling of the Faraday shield 108 into the body of the Faraday shield108. The side interface surfaces 252 of FIG. 2C can also operate as theside surfaces of the hub portion in FIG. 2D.

FIG. 2E illustrates an example where a hub 202″ is provided inaccordance with another embodiment of the present invention. In thisexample, the hub 202″ includes a Plenum that is integrated and extendedwith in the body of the Faraday shield 108. As the Faraday shield has aplurality of fins, it is possible that certain ones of the fins caninclude a cavity or cavities that can define an internal Plenum orchannels to allow for the air flow to cool the internal surfaces of theFaraday shield 108. In this implementation, the window 104, if placedproximate or on top of the Faraday shield 108 can also benefit from thecooled Faraday shield 108. Accordingly, it should be appreciated thatthe hub 202 can take on any number of configurations so long as an airflow can be provided to the hub and the airflow is used to remove heatfrom the hub, which is in physical contact or integration with theFaraday shield 108.

FIG. 2F illustrates an example where the Faraday shield 108 isundergoing a cooling operation by way of the airflow into and out of thehub 202, in accordance with one embodiment of the present invention. Asillustrated, the Faraday shield 108 can take on a temperature gradientwhich varies based on a number of factors. The factors can include theplacement of the coils above the Faraday shield, as well as heatgenerated within the chamber during plasma processing. In this example,it is illustrated that the center region of the Faraday shield 108 has acooler condition of about 110° C., and the peripheral edge also has acooler condition of about 110° C. Between the periphery of the Faradayshield 108 and the center region, the temperatures can be detected to beabout 130° C., surrounded by about 120° C.

By applying the airflow to the hub 202, heat conduction 270 occursthrough the Faraday shield from hot to cold. The arrows drawn across theFaraday shield 108 indicate the direction of heat conduction orconductive flow of heat across the Faraday shield 108. The conductiveflow of heat will be from hotter regions to the cooler regions, or inthe illustrated example, from the periphery to the center region of theFaraday shield 108. Without providing the flow of air for cooling to thehub 202 which contacts the Faraday shield 108 in the center region, thetemperature in the center region, in experiments, was measured to be atapproximately 140° C. However, by providing the cooling by airflowthrough the hub 202, the resulting temperature distribution shown inFIG. 2F was observed and measured. FIG. 5B-2, below, will illustrate thetemperature ranges observed and measured of the Faraday shield 108without cooling and with cooling provided by different flow ratesthrough the hub 202.

FIG. 3A illustrates an example of a Faraday shield 108 structure, whichwould face the window 104. FIG. 3B illustrates a modification to thecenter region of the Faraday shield 108. The modification to the centerregion of the Faraday shield 108 can include a recess for defining partof the Plenum established when hub 202 shown in FIGS. 3C and 3D areconnected to the Faraday shield 108. Therefore, the hub 202 shown inFIGS. 3C and 3D will have an open bottom and that mates to an airflowPlenum 302 formed in the center region of the Faraday shield 108.

The hub 202 will therefore have an interface surface 262 where theinterface surface 250 of the hub 202 will mate and connect. The meetingand connecting functions as physical contact between the Faraday shield108 and the hub 250, such that the heat conducts between the hub 202 andFaraday shield 108 in the center region. The Faraday shield 108, in oneembodiment, is also defined from a metallic material. The material issuch that heat conducts through and along the Faraday shield 108 andinterfaces with the metallic material of the hub 202. As shown in FIG.3C, the hub 202 will mate with the center region of the Faraday shield108, such that the interface surface 250 couples to the interfacesurface 262.

FIG. 3D illustrates one example, where the inputs into the hub 202 willtraverse as channels down the sidewalls of the hub 202 toward the baseof the hub 202 where the interface is made with the Faraday shield 108.The air will then circulate in the grooves of the air Plenum 302 of theFaraday shield 108 and then out of one of the channels within the hub102. Therefore, one or more input conduits 202 a can be connected to thehub 202 for delivery of fluid and one or more output conduits 202 b canbe connected to the hub 202 for removal of fluid.

The constructions of hub 202 shown in FIGS. 3C and 3D are only exemplaryin nature, and other constructions are possible so long as air can beflown into the hub 202 and removed from hub 202 to provide a continuousflow of air at a flow rate for removal of heat from the center region ofthe Faraday shield 108.

FIG. 4A illustrates another example of a hub 202-A with a single inputair conduit, in accordance with one embodiment of the present invention.In this embodiment, air is flown into the single input which distributesthe air circularly within a Plenum of the structure of hub 202-A. Theair is caused to flow in and out of the hub 202-A, such that thetemperature at the interface with the window 204′ and the interface withthe Faraday shield 206′ is reduced. In one embodiment, the hub 202-A ismade of a conductive material such that can conduct between the hub202-A and the window 104 and the Faraday shield 108. In this exampleconstruction, the hub 202-A has a curved step that allows contactbetween both the Faraday shield 108 and the window 104.

The curved step construction also allows for security placement withinthe center region of the window 104 and provides the contact with theFaraday shield 108, as shown in FIG. 4B. Again, the exemplaryconstruction of the hub 202-A was only provided to illustrate theflexibility and many configurations that a hub can take, so long ascontact is made between some of the surfaces of the hub and the Faradayshield 108, or both the Faraday shield 108 and window 104. In anotherembodiment, the hub can simply contact only the window 104 and not theFaraday shield 108, or only the Faraday shield 108 and not the window104.

FIG. 5A-1 illustrates an example of the temperature gradients observedby the window 104 under several conditions of cooling or no cooling, inaccordance with one embodiment of the present invention. The window 104shown in FIG. 5A-1 represents a cross-sectional half of the window, forpurposes of illustration only. The left side of each window 104 isapproximately the center region of the window 104, which is configuredto be placed over the Faraday shield 108. The rightmost section of thewindow 104 segment is considered to be the outer periphery of the window104.

In FIG. 5A-2, a number of flow rate settings for air flow through thehub 202 is shown, for comparison purposes. For example, conditions areshown for no cooling, which means no air flow through the hub 202. Anexample is shown for a flow rate of 1 CFM which impacts the temperatureof the window closest to the center region initially, and as the centerregion cools by way of the air traveling through the hub 202, heatconducts away from the periphery of the window 104 toward the centerregion, thus reducing the temperature of the window 104. An example isshown for a flow rate of 5 CFM which also impacts the window closest tothe center region initially, and as the center region cools by way ofthe air flow through the hub 202. An example is also shown for 10 CFMwhich in the experiment provides a larger impact on heat reduction ofthe window 104.

Although the heat reduction initially occurs near the center region ofthe window, which would be proximate to the hub 202 that may be incontact with the window or simply in contact with the Faraday shield108, a steady-state will eventually occur during processing. Thesteady-state will be when continuous airflow at the chosen CFM level isset, and processing continues over a period of time. During thisprocessing over the period of time, the window can be made to remain atsteady-state, such as at the temperature distribution shown when aparticular CFM level is continuously applied through the hub 202.

In other embodiments, a controller can be set when airflow is desiredthrough the hub 202. For instance, no airflow could be selected duringcycle times when the processing is stopped or progresses, and airflowcan resume or increase at different rates and remain at particularsettings during specific process conditions. In this manner, the windowcan be made to avoid cycling through set temperaturechanges/differences, e.g., transitions of very hot to cold or from coldto very hot. In other examples, the system can control that thetemperature differences are not more than 5 degrees in temperaturedifference, not more than 10 degrees in temperature difference, not morethan 15 degrees in temperature difference, not more than 20 degrees intemperature difference, or any other setting. In other words, bycontrolling when the airflow is provided to the hub 202, it is possibleto reduce the swings in temperature during process operations inaccordance with specific recipes executed through the chamber.

Reductions in swings of temperature variations can assure or reduce therisk of having polymer buildup on the inside of the Faraday shield 108facing the wafer from flaking polymer onto the surface of the waferbeing processed. Further, simply having elevated temperatures on theFaraday shield can damage the Faraday shield coatings, such as anodizedcoatings. These coatings may flake off or peel off at elevatedtemperatures, if the Faraday shield remains at such elevatedtemperatures, such as above 135° C. for extended periods of time or ifsuch elevated temperatures are used the lifetime of the Faraday shieldmay be reduced. It is believed that maintaining the temperature of theFaraday shield 108 at some constant or within some controlledtemperature variation not exceeding some predefined temperaturedifferential, material from polymer byproducts adhered to the Faradayshield 108 will remain adhered until a next cleaning operation isperformed.

FIG. 5B-1 illustrates an example of the temperature effects of havingthe Faraday shield 108 in thermal contact with the hub 202, in alocation proximate to the center region of the Faraday shield 108. Inthis illustration, half of a cross section of Faraday shield 108 isshown, where the leftmost portion is the portion that is closest to thecenter region and the rightmost portion is the portion that is near theperipheral region of the Faraday shield 108. As illustrated, the topFaraday shield 108 is provided with no cooling. No cooling means thateither the hub 202 is not connected or interfaced with the Faradayshield 108 or no airflow is provided to the hub 202. For instance, thecenter region of the Faraday shield with no cooling may reach atemperature near about 140° C. When an airflow of about 10 CFM isapplied to the hub 202, the center region of the Faraday shield can beshown to reach a lower temperature of about 110° C. At the same 10 CFM,the center region is shown to reach a temperature of about 130° C.

The graph shown in FIG. 5B-2 illustrates the various impacts ofdifferent flow rates, such as 10 CFM, 5 CFM, 1 CFM and no cooling. Asdiscussed above, it is believed that by applying the hub in physicalcontact with the Faraday shield 108 or providing a hub that allows aPlenum within the hub to flow a fluid/air to the Faraday shield 108 nearthe center region, the center region of the Faraday shield 108 willreduce in temperature. This reduction in temperature near the Faradayshield center region will cause a conduction of heat from regions of theFaraday shield 108 that are hotter than the region near the centerregion where the hub is providing the airflow. Although temperature willstill vary across the length of the Faraday shield segment shown in FIG.5B-1, as confirmed by experiment, it is possible to approximate what thetemperature will be across the Faraday shield surface for different flowrates of air.

Nevertheless, the experimental data confirms that increase flow ratesassist in reducing the temperature near the center region of the Faradayshield which also assist in bringing down the temperature between thecenter region and peripheral region. For example, the graph of FIG. 5B-2shows that the region between the center region and the peripheralregion can be decreased from a temperature that is over 135° C. down toa temperature that is approximately 130° C. when approximately 10 CFMflow rate is provided to the hub 202, which is in contact or thermalcontact with the Faraday shield 108.

FIG. 6A illustrates one flow of method operations that may be utilizedto operate a plasma chamber that uses a hub for providing a flow of airfor cooling a Faraday shield, in accordance with one embodiment of thepresent invention. In operation 302, a chamber with a Faraday shield isprovided. The chamber is used for processing semiconductor wafers, andin particular use for etching operations. The Faraday shield is providedin a configuration that faces the processing wafer within the chamber.In operation 304, a plasma is generated in the chamber. The plasma isgenerated utilizing gases that are configured and selected for etchingparticular surfaces on semiconductor wafers during fabrication. Thegases are then excited utilizing power provided by RF power deliverysystems. The gases, under pressure, are then converted into a plasmausing the power, such as RF power provided by the TCP coils and or powerprovided to the chuck on which the wafer sits or is placed duringoperation.

In operation 306, a hub is provided with a flow Plenum and is interfacedwith a center region of a Faraday shield. The interfacing with theFaraday shield is such that thermal conductivity can take place betweenthe Plenum of the hub and a surface of the Faraday shield in contactwith the hub or channels that enable flow of air or fluids through thehub so as to thermally conduct with the Faraday shield. The flow of airprovided to the hub and the Plenum of the hub enable the flow of air toconduct heat away from the center of the Faraday shield, by allowingheat to transfer and conduct through the Faraday shield from theperiphery of the Faraday shield to the center region of the Faradayshield closest to the hub, where airflow is provided.

In operation 310, the airflow can be maintained to the hub, so that theheat conducts through the Faraday shield from the periphery of theFaraday shield to the center region. Maintaining the airflow can becontrolled by a controller of the chamber setting of when the airflow isconducted, and the level of airflow can be set based on a recipe. Therecipe can be associated to a processing recipe utilized for etchingwafers. The processing recipe can identify periods of time when theairflow will be provided, and the flow rates at which the airflow willbe provided through the hub so as to maintain the temperature desired atthe center region, and the resulting temperature gradients across theFaraday shield.

FIG. 6B illustrates another embodiment of utilizing a hub for aircooling a Faraday shield. In 320, a Faraday shield is provided with acenter region that extends to a periphery. The Faraday shield is definedfor use in the chamber, such that the Faraday shield is exposed to theplasma produced in the plasma etching chamber. In operation 322, a hubwith a flow Plenum is provided. The hub is configured to interface viaan interface surface with a center region of the Faraday shield. Inoperation 324, an interface surface of the hub can also be defined tocontact a dielectric window that may be residing above the Faradayshield. Having the hub contact the dielectric window is optional.

In operation 326, a flow rate of air into the hub is selected. The flowrate can be selected for a period of time, based on a recipe, or at thecontrol of the user during operation, or adjusted from time to time. Itis believed that a higher flow rate will increase the ability to reducethe temperature of the Faraday shield near the center region, and canalso impact a reduced temperature of the Faraday shield toward theperiphery.

In operation 328, air is flown into the flow Plenum of the hub allowingthe air to provide heat conductive contact with the center region of theFaraday shield, and optionally with the dielectric window. Again, theflow of air can be managed and set based on a predefined recipe. Thepredefined recipe can be adjusted or correlated to the plasma etchingrecipe utilized for one or more wafers. In operation 330, the flow ratesof air can be maintained to reduce a temperature of the center region ofthe Faraday shield. This will allow heat to conduct through the Faradayshield from the periphery toward the center region of the Faradayshield.

As described above, one embodiment utilizes compressed dry air to coolan internal Faraday shield. However, it is believed that using a higherairflow of air, and not necessarily the fact that it is compressed dryair, will assist in reducing the temperature of the Faraday shield wherethe higher airflow is provided via a hub or structure. The “central airdelivery hub” which mates to the center section of an internal Faradayshield therefore enables the delivery of the higher airflows, which canreduce the temperature of the Faraday shield. It is through this hubthat the air comes into contact with the Faraday shield and thus allowscooling of said shield. It should be noted that the air flow does notactually go into the chamber, it just circulates around the hub or isprovided in close proximity to the Faraday shield via the hub.

The hub and its Plenum reside outside of the chamber, and no airflow isprovided into the chamber to assist in the cooling. And, heat transferout of the Faraday shield occurs via conduction. That is, the air flowcools the center of the shield such that heat is conducted through theshield itself from the edge/middle of the shield. The airflow does notdirectly remove heat from the edge/center of the shield via conduction.Thus, the higher airflow assist in providing a higher heat transfer rateby conduction through the Faraday shield toward the cooler center regionwhere the airflow is provided.

In some embodiments, a chiller is provided to cool the fluid beforebeing provided to the hub 202. In this manner, the fluids coupled to achiller reduce a temperature of the fluids before delivery by the fluiddelivery control. A chiller may include a refrigerant system that coolssupply lines or flows fluids or gases to transfer cold temperatures tolines or supplies. The chiller can be a jacket around supply linescoming to or leaving the fluid supply control 210. The chiller may coolthe air as low as −50 degrees C., or lower. In other embodiments, thechiller will just cool the air/fluid to just above freezing.

It should be understood, however, that the simple flow of air andincreasing the flow rate of air at room temperature 20 degrees C. (i.e.,without chilling) will function to induce or start the conduction ofheat out of the Faraday shield using the hub.

While this invention has been described in terms of several embodiments,it will be appreciated that those skilled in the art upon reading thepreceding specifications and studying the drawings will realize variousalterations, additions, permutations and equivalents thereof. It istherefore intended that the present invention includes all suchalterations, additions, permutations, and equivalents as fall within thetrue spirit and scope of the invention.

What is claimed is:
 1. An apparatus for use in a plasma chamber,comprising: a Faraday shield for coupling to a top region of a plasmachamber, the Faraday shield has a process side that faces inside of theplasma chamber and the Faraday shield has a center opening; a hub havingan internal plenum for passing a flow of fluid received from an inputconduit and removing the flow of fluid from an output conduit, the hubhaving sidewalls and a center cavity inside of the sidewalls for anoptical probe, the internal plenum is disposed in the sidewalls, the hubincludes an interface surface that is in physical contact with a backside of the Faraday shield, the physical contact provides for a thermalcouple to the Faraday shield at a center region around said centeropening; wherein the center region of the Faraday shield includes aplenum that mates with the internal plenum of the hub, such that theinterface surface of the hub surrounds the plenum of the Faraday shield,wherein the thermal couple to the center region of the Faraday shield isdefined at the interface surface.
 2. The apparatus of claim 1, whereinthe plenum of the hub and the plenum of the Faraday shield define a loopinto and out of the hub, and the flow of fluid is maintained outside ofa processing volume of the plasma chamber.
 3. The apparatus of claim 1,further comprising, a gas injector defined in the center cavity of thehub for providing process gas into a processing volume of the plasmachamber, when the apparatus is installed with the plasma chamber.
 4. Theapparatus of claim 1, wherein the Faraday shield has a disk shape withan outer periphery that couples to chamber sidewalls that define the topregion of the plasma chamber, and the hub and the Faraday shield arecoupled together at the interface surface.
 5. The apparatus of claim 1,wherein the flow of fluid provides for a reduced temperature at thecenter region of the Faraday shield, the reduced temperature in thecenter region induces a conductive flow of heat through the Faradayshield toward the center region.
 6. The apparatus of claim 1, whereincoils for supplying radio frequency (RF) power are disposed over adielectric window, the dielectric window is a top part of the plasmachamber, and said coils are oriented around the sidewalls of the hubabove the dielectric window.
 7. The apparatus of claim 1, furthercomprising, a fluid delivery control coupled to the input conduit of thehub, the fluid delivery control is configured with a flow rate regulatorfor setting a flow rate of the flow of fluid through the internal plenumof the hub; and a fluid removal control coupled to the output conduitfor removing the flow of fluid from the internal plenum of the hub. 8.The chamber of claim 7, wherein the fluid delivery control deliversfluids selected from air, gases, liquids, or mixtures thereof.
 9. Thechamber of claim 8, wherein the fluids are coupled to a chiller forreducing a temperature of the fluids before delivery by the fluiddelivery control.
 10. The apparatus of claim 1, wherein the opticalprobe is defined for monitoring process conditions in a processingvolume of the plasma chamber during use.